Piston and packing construction



G. N. HEIN PISTON AND PACKING CONSTRUCTION Dec. 8, 1925 Filed Aug 26. 1924 Jhven Z1 01 )3, v affarrzqq,

Patented Dec. 8, 1925.

GEORGE N. HEIN, OF SAN FRANCISCO, CAIJIFORNIA- PISTON AN D IIIAGKIING' CONSTRUCTION.

Application filed August 26 To all whom it may concern: I Be it known that I, GEORGE N. Ham, a citizen of the United States, residing at city and count of San Francisco, and State of California, have invented certain new and useful Im rovements in Piston and Packing Construction, of which the following is a specification.

This invention relates to a piston and packing construction adapted for use in hypodermic syrin es.

One object of t e invention is to' produce a packing having a relatively small contacting surface with the syringe barrel wall, thus reducing to a minimum piston friction and liability of the packing adhering to the barrel surface when dry. Another object is to provide a piston and packing which may be easily inserted without damage to the packlng into the barrel of a hypodermic syringe, thefmouth of which is sharp, uneven, or of varying contour. Further objects are to construct an elastic packing adapted to overlie the peripheral edge of the portion of the piston, providing a yield able leak-proof joint, and to provide an expansible mounting for the packing-adapting the packing pressure against the barrel wal to be varied.

With the above mentioned and other objects in view,-the invention consists in the novel construction and combination of parts hereinafter described, illustrated in the accompanying drawin s, and set forth in the claims hereto appen ed, it being understood that various changes in the form, proportion, size and minor details of construction .within the scope of the claims maybe resorted to without departing from the s irit or sacrificing any of the advantages 0 the invention.

In the accompanying drawings, Figure 1 is a vertical sectional view of the syringe showing the piston in elevation.

Fig. 2 is a vertical sectional view. taken along the line 22 of Fig. 1, showing the piston and packing construction.

Fig. 3 is a plan view of the syringetaken along the line 3-3 of Fig. 2.

Fi 4 is a vertical sectional view of the tubu ar washer adapted to 'overlie'the peri heral edges of the piston. j

ig. 5 is a view in section of an adjustable form of the piston head-end of themodifiedform of piston.-

, 1924. Serial no. 734,210.

- Fig. 6 is an end' view of the structure illustrated in Fig. 5.

In the drawings, wherein like characters of reference designate corresponding parts, 1 indicates a cylindrical tubular barrel open at one end to admit of the piston2 to be inserted thereinto and of reciprocating movement therein, and detachably coupled in any suitable manner to the outlet or' discharge end of the barrel is a hypodermic needle 3'. The end of the piston 2 mounts an elongated tubular packing washer 5 positioned on the piston and constructed in a manner hereinafter described. .The lower end 2' of the piston 2 is of a smaller diameter than its remainin portion and said lower end portion is clrcumferentially grooved as .at 6, forming the spaced shoulders 4 and 4', the shoulder ibemg disposed zit-substantially right an les to the base of-the groove and the shou der 4' being inwardly beveledas at 4, the object of the bevel-being to retain the washer in position on the piston when rearward linea movement is transmitted thereto. The extreme end-of the iston 2' is circumferentially beveled inward its peripheral ed e toward itscenter as at 7. The tubular pac ing washer 5 of rubber or other elastic material provided with a bore of normal diameter less than'the diameter of the reduced portion of the piston, thus when stretched thereover providing a ly from leak-proof joint between said reduced portion and'the inner surface of the packing.

The packing is also of a thickness to extend beyond the surface of the main body of the piston at. the point of its overlying the reuced portion 2'. The ends of the packing 5 are inwardly beveled as at 8 and 8, one to conform to the contour of the inwardly beveled wall 4 and the other to lie i-na plane substantially parallel with the. end wall of the piston as clearly illustrated in Figs. 2 and 5.

hIn mounting the washer 5 in t e sitionon iston the piston is first with rawn from the barrel and the packing is stretched endwise over the'end ortion 2' of the piston until the end of t e washer substantially contacts with the shoulder 4, the elasticity of the packing causing the same to tightly grip the base of the annular groove 6 and the outer end thereof to tightly grip the beveled surface 7, providiigfi a s ace 4 immediately in rear of'the on] or 4. The

- tact with said surface, afior 'ng a leak-proof joint. The stretching oi the member 8 over the flange causes that portion of the elastic material at the point of contact with the barrel to be distendedv or com ressed,

.and consequently 'is' more compact t anthe rubber or elastic material on either side of this point ofcontact, the elastic material end.

gradually decreasing in compactness or density asitrecedes from its point of greatest stretch. V V

The modification illustrated in Figs. 5 and 6 employ the elastic. packing illustrated in Fig. 4 w1th an expansible head 10 splitlongitudinally at right angles as at 11 and threaded into a bore 12 in the main body of the piston. Bea are formed respective y onthe main bod of the .pistonand the head above the three edseat cooperate to control the'expansion or contraction of the s lit end,.dependent on .the ad'ushnent of t e headin the piston in adjusting tech-for. example, a screw driver, may be inserted into slots 11 when it is desired to vary the diameter withjts end wa'lliterminating 2 and 3; f

the exception of the adjustability the head is the same as that illustrated in. Figs.- 1,

. Iclaim:-

1. A piston and packing constructionfor syringes comprisinga piston having a body adapted to fit within the syringe barrel, the

' end of said piston being circumferentially grooved, afl'ording a circum'ferential flange r'extending' outwardly 'at ri ht angles from the end or said piston, the diameter of which is less than the diameter of the remainder of the piston, the outerface of said flange inwardly. beveled and a. tubular elas-' ticpacking fitted over said "reduced piston rtion and said flange with itsend overying said. beveled portion of theflange and I in a plane .subata'ntially'parallel -and flush with the end of the piston,.the portion of said packieg 'in? nu.- of-.said"llange- -being spaced mm the' rear.-:fla'nge-w afio thereeeption of Salinger;

. reaeure-. between the flange periphery and. a the ems-wan: ,2. packin'geonatruction for" I e increase of shoulders 13 and 14 of the piston, and a tubular elastic 1 ing of a normal diameter less than that of anareafor end of the packing.

syringes comprisin a iston havin a bod adapted to fit within the syringe b rrel, a expansible h'ead threaded the pistonand including a longitudinally slotted yieldable body of a diameter. less than that of the piston, said head being formed at one end with an annular flange having an inner wall dis osed at substantially right angles to the ody wall and its outer time being inwardl beveled, toward the-end of the head, a tu ular elastic packing fitted over the head with its end overlying said flan e and the beveled portion bevelled portion of the flange and with its end wall terminatin' in a plane substantialliy; parallel with an flush with the end of t e piston whereb the internal pressurein the syringe barre will be appliedte said I 'paaking end to force that portion thereofthe packing and inall o her 188P00tSW1th" of over y in -the bevelled faceof the flange longitudina y of said bevelled surfaces. 4. A piston and packing construction for syringes comprising a piston having a flange extending outwardly at right angles from one end, the outer face of; said flange being bevelled to afiord a surface facing the end packthe'flange and stretched over the same, the end of said packing being bevelled to correspond with the bevel of the flange wherebythe packin end wall will lie parallel with the end 0 the piston.

5. In combination with a piston having a flanged end, a piston packing for stretching over said flan ed end with its end terminating substantia y flush with the iston end, the same. comprising-anelastic tu ular body of a normal inner diameter less than that of the flanged end, one end of said packing being. circumferentially bevelled from the ininto the head of ner to the outer edge toward the opposite In testimony whereof I have signed my name to this specification." 1

1 u-JHGE BGE N. HE IN. 

